Blood components are separated from units of human blood and utilized for separate therapy in patients. For example, blood plasma may be administered without red cells. Also, the packed red cells can be administered to a patient with a minimum of plasma or other suspending solution. Furthermore, platelets or white cells may be administered as specific components. Also, platelet-poor plasma is another product from blood utilized in various forms of therapy.
The invention of this application relates to a centrifuge which can be used to obtain, for example, separate portions of platelets, plasma (including platelet-poor plasma), other white cells, and packed red cells. The device of this invention can operate to process, in a continuous operation, an unlimited amount of blood from a donor, processing the blood to separate and return the red cells to the donor, and to harvest, as desired, the white cells, platelets and plasma. The centrifuge bowl or container of this invention utilizes a radially thin, circumferential flow path for the blood and plasma being processed, to provide a long, thin circumferential flow path in which a continuous process of separation may take place. As a result of this, a sweeping action may take place over the thin, sedimented layer of the slightly heavier particles such as the blood cells, to move the slightly lighter particles (for example the white cells) downstream with respect to the red cells. This permits the use of sharply lowered G forces than is customarily used in conventional blood separation, with the slightly lighter cells being urged to move downstream more quickly than the slightly heavier red cells, to provide a more efficient cell separation.
Also, the thin, circumferential operating path provides a very short sedimentation distance, no more than the restricted width of the path. This also provides the advantage that the centrifuge bowl container of this invention has a low blood volume so that a relatively small amount of blood is removed from the donor at any one time while at the same time facilitating the sedimenting of red cells and protecting the platelets from the known, undesirable effects of high G forces in excess of one thousand Gs.
Furthermore, the device of this invention permits the accumulation of white cells and platelets during continuous operation, in which the red cells are sedimented along the circumferential path and then withdrawn for reinfusion to the patient on a continuous or repeating basis. At the same time, the white cells and/or platelets, which generally comprise less than one percent of the blood volume, can be accumulated during the operation so that large amounts of white cells and platelets can be harvested in the single operation.
The above objectives are accomplished in the apparatus of this invention with minimal shear stresses being placed on especially the white cells and platelets.
The invention of this application effectively provides an efficient, sterile means for obtaining blood components from a donor or from reservoirs on a semi-automated basis, utilizing a disposable container of novel configuration.